Batteries of high energy density are desirable in a number of end uses. High energy density batteries are those which generally can produce at least 50 watt hours per pound (for a secondary battery). A number of secondary batteries have been designed to improve energy capacity. Such a system is described in U.S. Pat. 3,328,202 wherein liquid bromine is absorbed on an activated charcoal electrode. Another concept is that described in U.S. Pat. No. 3,236,694 wherein cesium bromide is used as electrolyte and used to absorb the electroactive material. Numerous patents describe the use of aqueous metallic halide solutions as electrolytes with halogens as electroactive materials. One of the earliest, U.S. Pat. No. 1,377,722 describes the use of liquid chlorine under pressure. An early reference which describes the preparation of chlorine hydrate by the separation of chlorine from gas mixtures is British Pat. No. 13,647 published 1887. This reference and French Pat. No. 393,332 describe the use of chlorine gas from chlorine hydrate in primary batteries. Another chlorine battery is described in U.S. Pat. No. 3,134,698. The difficulty with the prior art batteries is that there has been no real method described for producing a material which could be generated from and be reconstructed into the electrolyte in order to continuously charge and discharge a battery.